Layering at free liquid surfaces - art. no. 166101

We show that simple liquids, with appropriate choices of the isotropic pair interaction, may exhibit surface layering above the melting temperature. R esults for the liquid surface have been obtained by Monte Carlo simulations in slab geometry. Surface layering appears at temperatures below approxima tely one-third of the critical temperature for very different choices of pa ir interaction. The high melting temperature of the Lennard-Jones crystal p reempts the observation of the oscillatory density at the free liquid inter face, while model pair interaction potentials, built to reproduce some prop erties of mercury and the alkali metals, have low melting temperature, unco vering the region of surface layering.